There are many instances in the design and manufacture of machinery in which it is important to assemble two parts together very accurately and permanently. Nowhere is this more important than in the manufacture of a centrifugal pump where the impeller is designed with internal passages. These passages must be exactly alike, otherwise an "odd" passage can cause pulsations in the hydraulic pressure. These pulsations appear in the entire system to which the pump is connected and are almost always undesirable.
Now, in attempting to remove differences in the shapes and sizes of the passages, impellers have been made in two parts which are half of each passage in each half. This permits the half passages to be carefully machined. This would, of course, not be possible if the impeller were made in one piece, because of the curved shape of the passages. The two halves were joined together by rivets or threaded fasteners after the machinery operation. However, no matter what type of means was used to join the two parts, it was impossible to match the machined cavities to provide a smooth continuous passage. Furthermore, all fastening means tended to loosen and thus destroy the integrity of the impeller. These and other difficulties experienced with the prior art devices have been obviated by the present invention in a novel manner.
It is, therefore, an outstanding object of the invention to provide a centrifugal pump capable of delivering hydraulic pressure without pulsations.
Another object of this invention is the provision of method of producing a centrifugal pump impeller with multiple internal passages that are accurately similar in shape and size.
A further object of the present invention is the provision of method of joining two members of a machinery part in such a manner that they are permanently joined in accurate relationship with one another.
It is another object of the instant invention to provide a centrifugal pump impeller which is simple in construction, which is inexpensive to manufacture, and which is capable of a long life of useful service with a minimum of maintenance.
With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.